Apparatus for abrasively treating objects



Oct. 11, 1960 G, w, scylgERn/{Alu-v 2,955,387

APPARATUS FOR ABRASIVELY TREATING OBJECTS Filed Nov. l0. 1958 2 Sheets-Sheet 1 /f n /2 4 ,/0 /3 L!! @25 1W i y y, v 1 y I 9 u 3+* am" 40 T1" |11 y i 'lillhi Oct. `1l, 1960 G. w. sDERMAN 2,955,387

APPARATUS FOR ABRASIVELY TREATING OBJECTS Filed Nov. l0, 1958 2 Sheets-Sheet 2 .Z-N V EN TUF? GLU. sanel-mn/v United States Patent O APPARATUS FOR ABRASIVELY TREATING OBJECTS.

George W. Sodermam Alpine, NJ., assignor to Western Electric Company, Incorporated, New York, NY., a corporation of New York Filed Nov. 10, 1958, Ser. No. 772,870

7 Claims. (Cl. 51`8) This invention relates to article working apparatus, and particularly to an apparatus for removing excessive metal coverings from quartz crystals.

In the manufacture of wafer-like quartz crystals for use in the communication arts, relatively thin metallic coatings areformed on the opposing sides. Usually the coatings on each side of the crystal are dividedinto two or more areas to form electrical-ly separate units and quite frequently it is necessary to deviate from a straight dividing line as the desired resultant configurations of the areas are quite irregular and consequently diicult to obtain. In such instances the metal is uniformly applied and subsequently masked to expose the coating which must be removed, for example by a pumice blasting operation, in order to obtain the proper division. However, it is vital that the exposed areas of the coating be entirely removed from both sides of the crystal without material abrasion of the crystal surfaces. The slightest amount of metal left on the dividing line will provide an undesired conductive path between the units and conversely excessive and unequal blasting will impair `the electrical properties of lthe units. Thus, manual removal or usage of a pair of purnice jets simultaneously blasting the crystals opposing surfaces passing therethrough is not desirable because the required identical and constant conditions on the opposing surfaces would be difficult to obtain to the required limits of accuracy.

rl`he object of this invention is to obtain identical division lines on various surfaces of articles such as quartz crystals.

Broadly, this invention insures that both surfaces to be divided be exposed to substantially identical abrasive actions and this is accomplished by using one jet operating under stabilized conditions and moving both surfaces to be abr-aded along the same path at the same speed.

In general the crystal is carried through an abrading chamber wherein an abrasive jet is actuated to remove the coating thereon. Subsequently, the crystal is auto-` matically turned 180 and again passed through the chamber wherein the same jet is discharged to remove the coating on the opposing surface.

Specifically, the invention comprises an article working apparatus which includes a holder loaded with an article and connected to a motor which drives a threaded member in a sleeve attached to the holder so as to draw the holder downwardly into an abrading chamber past an abrasive jet which i's actuated to blast abrasive material upon the article passing therethrough. At the end of the downward movement, the motor is automatically reversed and the sleeve, which is free to follow the rotation of the shaft, has a disc mounted thereon for limiting the rotation of the sleeve to a predetermined angular movement thereby exposing another surface of the article to the action of the same jet as it passes through the `chamber on its upward movement to its original position outside the chamber. The automatic reversevmovement of the disc insures that the artcles surfaces are sub- Patented Oct. 11, 1960 jected to the same conditions during the reciprocating action of the holder Ithereby obviating any differences in the formation of the desired lines of division,

Other objects and advantages will be apparent from -the following detailed description when considered in conjunction with the accompanying drawings, wherein Fig. l is a front elevational view of the apparatus, portions thereof being shown in section;

Fig. 2 is a fragmentary top view of the limiting rotary movement of the apparatus;

Fig. 3 is a side elevational view taken along the line 3-3 of Fig. 1.

rlhe apparatus, as shown in the drawings, includes a work bench 10 whereon a work holder 11, for holding an article such as a quartz crystal, has laterally opposing slots 12, 13 for exposing surfaces of the crystal secured in a masking plate (not shown) positioned in the work holder. The holder 11 is connected to a shank 14 which is secured to a disc support by stud bolt 16. The support 15, mounted to a tubular threaded sleeve 17 by screw 18, is driven by the threaded member 19 and shaft 20 connected to the motor shaft Z1 of the reversible motor 22.

As seen in Fig. l the mechanism is in starting position and after a quartz crystal has been uniformly coated with precious metal and subsequently masked, it is -inserted into the holder 11. The motor 22, started by pressing start button 23, rotates the threaded member 19 in tubular sleeve 17 and, as hereinafter explained, draws the crystal holder 11 into an abrading chamber 24. As the holder 11 enters the chamber, a collar 25 mounted on sleeve'17 contacts a microswitch 26 that turns on an abrasive jet 27 which forces an abrasive, for example, pumice, under air pressure against the masking plate and crystal surface exposed in slot 12 removing the exposed preci-ous metal plating thereby sub-dividing the blank electrically into two crystal plates. It is to be noted Athat collar 25 keeps microswitch 26 energized during the downward movement until it clears the microswitch so that the abrasive blast is operated only when the crystal passes through the chamber. Obviously different length collars can be used for varying the blasting time as required. The desired amount of pressure utilized to eject the abrasive material is regulated by a pressure control gage 23 of a pressure system generally utilized in the art. During the blasting operation the pumice laden air is drawn from chamber 24 through a tube 29 by an exhaust unit 30 to prevent the pumice from escaping onto other parts of the apparatus.

During the downward stroke of the sleeve 17, a disc 31 mounted on the disc holder 15 and having a semicircular groove 32 therein, rides along a guide rod 33 at the end portion 34 of the groove restricting the sleeve from rotating on its axis and enabling it to move ver'- tically on the rotating threaded member 19 (Figs. 2 and motor 22 thereby rotating the sleeve 17 and disc 31 counterclockwise 180 until the opposing end portion a6 of the groove 32 is stopped by the guide rod 33. As this occurs the shank 146 and work holder 11 also rotate 180 resulting in the opposing surface of the crystal being exposed through slot 13. It is to be understood that the groove 32 of disc 31 need not be limited Ito 180 as it may be extended or diminished in size depending upon the amount of angular movement required for exposing another surface of the article to the work station. For example, it may be desired to expose two surfaces of a triangular shaped article and consequently a groove in the disc would be required.

After the rotation of the sleeve 17 has been ,restricted by the guide rod 33, the sleeve and work holder move upwardly upon the threaded member 19 and as the holder nears the abrading chamber 24, the collar 25 strikes microswitch 26 causing the abrasive jet again to discharge a spray of pumice upon the masking plate and opposing surface of. the crystal exposed through slot 13'thereb'y removingthemetal covering and producing a groove identical to that found in the opposing surface. The conditions present in the first blast on one surface of the crystal are maintained in the second blast on the opposing surface as equal amounts of abrasive material under a constant pressure are discharged when the collar 25 again operates microswitch 26. Also, the crystals opposing surface has been automatically turned by the action of disc 31 so as to similarly position it to traverse a similar jet action. When the abrading action is completed, work holder 11 passes out of the chamber to the top of work bench 10 and disc 31 strikes microswitch 41 causing the motor to stop. The crystal is removed and a new one inserted to commence the operation of another cycle. A

The possi-bility of grit, .dust or pumice` Working into t-he reciprocating mechanism and disturbing the desired constant conditions is eliminated by the usage of a flexible cover 37, such as a chamois cloth, which is secured to the motor and sleeve by ring clamps 38, 39 respectively. A guide 40, supported by member 42, has an oversize centrally located aperture for -the shank 14 and a plurality of equidistant set screws therein (not shown) prevents the aperture from clogging With any abrasive material which may have escaped. Consequently rnandatory constant conditions can be maintained and identical grooves produced in the uniform metallic coverings on opposing surfaces of wafer-like quartz crystals.

It is to be understood that the above described arrangements are simply illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which `will embody the principles ofthe invention and fall within the spirit and scope thereof.

What is claimed is:

1. An article working apparatus, which comprises a Work fixture loaded and unloaded outside an apertured work chamber within the apparatus, a normally inactive unit for projecting a stream of material into the chamber, means for driving the xture into the chamber to expose a rst area of the work to the stream, means on the driving means for activating and deactivating the stream on the work moving past the unit, means for exhausting the chamber to prevent escape of the material onto other parts of the apparatus, a member on the driving'means for rotating the fixture and reversing its direction of motion, and means for limiting the rotation of the iixture to expose a predetermined different area of the work to the stream.

2. In an article working apparatus having an aperturedV work chamber and abrasive projecting means for projecting a stream of material into the chamber, means for traversing an article past the stream which comprises a holder rotatable to expose iirst and second surfaces of the article to the stream, rotatable driving means for moving the holder axially to progressively subject the first surface to the action of the stream, means actuated in a predetermined position of the holder for reversing the direction of the driving means and means responsive to the reversal of the driving means for limiting the rotation of the holder to align the second surface with the stream. e

3. A system -according to claim 2 in which the abrasive projecting means is the normally inactive abrasive blasting tool and in which means driven by the rotatable driving means activates the tool as the holder moves into the path of the stream.

4. An apparatus 'for subjecting a plurality of surfaces of an article to the action of an abrasive jet comprising a rotatable holder for `the article, an apertured work chamber in the apparatus, rotary driving means for moving a first surfaceof the article through the chamber past the jet, a driving connection between the driving means and the holder, means for reversing the motion of the article with respect to the jet and means for limiting the rotary motion of the holder to the angle required to expose the second surface of the article to the jet.

5. An apparatus as found in claim 4 in which'the limiting means comprises a member on the driving connection having an arcuate groove therein, and a xed guide rod extending through the arcuate groove.

V6. An apparatus for forming identical grooves in a coating on opposing sides of an article which comprises a holder for exposing first and second surfaces of the article, a worm, a sleeve connected to the holder and having a threaded inner surface meshed with the worm, an abrading chamber, a reversible motor connected to the Worm for passing the holder from a starting position through the abrading chamber, a unit for directing a constant stream of material into the chamber to remove the coating on the first surface area of the article passing through the chamber, a member mounted on the sleeve for reversing the motor, a collar mounted on the sleeve, and a switch operated by the collar for activating and deactivating the abrasive unit as the article passes through the chamber.

7. An apparatus for forming identical grooves in a coating on opposing sides of an article which comprises a holder for exposing rst and second surfaces of the article, a Worm, a sleeve connected to the holder and having a threaded inner surface meshed with the Worm, an abrading chamber, a reversible motor connected to the worm for passing the holder from a starting position through the abrading chamber, a unit `for directing a constant stream of abrasive material into the chamber to remove the coating on the tirst surface area of the article passing through the chamber, a collar mounted on the sleeve, a switch operated by the collar for activating and deactivating the abrasive unit as the article passes therethrough, a member mounted on the sleeve for reversing the motor and having an arcuate groove therein, and a xed guide rod cooperating with the arcuate groove for limiting the rotation of the sleeveon the worm to expose the second surface area of the article to the abrasive stream when passing through the abrading chamber back to starting position.

References Cited in the iile of this patent UNITED STATES PATENTS 

